Radio condenser system and method of adjusting the same



May 14, 1929. A. s. BLATTERMAN RADIO CONDENSER SYSTEM AND METHOD OF ADJUSTING THE SAME Filed Aug. 19, 1925 Qvwawioz 1 mm fisfizaizzman 7 7 Patented May 14;, 1929.

UNITED STATES PATENT OFFICE.

ALBERT S. BLATTERMAN, OF NORTH ASBUBY PARK, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO B. M. C. PATENT COMPANY, OF TRENTON, NEW JERSEY,

A CORPORATION OI NEW JERSEY.

RADIO CONDENSER SYSTEM AND METHOD OF ADJUSTING- THE SAME.

Application filed August 19, 1925. Serial No. 51,096.

My invention relates to variable radio apparatus and more particularly to radio condensers commonly used for tuning the circuits of sending or receiving apparatus and has particular reference to apparatus of this character in which a plurality of Variable condenser elements are adapted for simultaneous or coordinated action.

My invention is applicable to radio appa ratus which employs several tuned circuits which are simultaneously tuned by means of a single control, in which case it is essential that a given movement of the control apparatus should produce simultaneously equal or other predetermined changes of capacity in each of the several circuits, and also to radio apparatus in which a plurality of circuits are simultaneously tuned by separate control ling means, and in which it is desired to secure tuning to a desired wave length in each circuit at a predetermined dial indication.

I have chosen to illustrate my invention in connection with the first of these cases, showing three simultaneously varied condensers operated by a common control means to produce equal changes in capacity upon operation of the control means.

In Figure 1 of the drawing, I have shown a side view of such an apparatus and in Figure 2, an end view thereof.

Referring to Figure 1, the apparatus may comprise a baseboard 1 upon which is mounted a panel 2 and a plurality of supporting brackets 3, 4: and 5. Upon each of these brackets the stator plates 6, 7 and 8 of the condensers are fixedly mounted. Projecting through the panel 2 is the shaft 9 carrying the operating knob 1'0, and having fixedly mounted upon it the rotor plates of the condensers 11, 12 and 13. Each condenser is provided with a rotor plate 1 1, 15 and 16 which is mounted to move axially upon the shaft 9 and to be held in an adjusted position by means of the set screws 17, 18 and 19. To prevent rotary movement of the adjustable rotor plates 11, 12 and 13, I preferably flatten the shaft 9, as indicated, at 20 so that the movement of these plates is purely axial.

It is well known that in case of an apparatus such as has been described, that it is essential that the three variable condensers have substantially identical capacity at all angular positions of rotation of their movable elements. Since the quantities dealt with are extremely small, it has been found practically impossible to build condensers of the usual type with sufficient accuracy to answer this fundamental requirement and it is consequently almost impossible to secure the desired result.

I have discovered that as a practical mat ter, the variations of the capacities of the several condensers at their various angular positlons are unimportant, provided the condensers are so constructed as to have equal maximum capacities, and that if the maximum capacities of the condensers are substantially identical it is entirely possible with ordinary manufacturing processes to construct the condensers so nearly alike that their capacity will be substantially identical at various angles of rotation. The variation in capacity of condensers is due in most cases to such manufacturing variations as will result in the axial displacement of the entire set of rotor plates so that the rotor plates do not mesh exactly midway between the stator plates; slight departures of the plates from the true plane; variations of thickness of the spaces between the stator plates, and the like. All of these variations affect the maximum capacity of the condenser and the substantial uniformity of variation of the capacity due to rotation of the plates may therefore be secured by compensation of the maximum capacity to make the maximum capacity of thie several condensers substantially identica y In the practice of my invention I turn all of the condensers to their position of maximum capacity, that is to the position in which all of the plates are fully meshed and then by connecting a capacity bridge, or other suitable known means for determining capacity, across each condenser individually I adjust the maximum capacity of the three condensers to substantially the same value by moving the movable plates 14, 15 and 16 toward or away from the last stator plate. This adjustment is not particularly fine and is easily made. When this adjustment is determined, I lock the movable plate in position by means of the set screws.

It will be apparent to those skilled in the art that other means of varying the maximum capacity of the condensers might be used instead of the simple means I have described, and that my invention may be applied to securing any desired predetermined capacity relation of the condensers other than identity in capacity value. I therefore do not wish to confine myself to the precise details of the apparatus illustrated, or the method I have described.

Claims:

1. In a radio receiver, in combination, a plurality of condensers adapted to adjust as sociated tuned circuits to corresponding wave lengths at corresponding settings of the condensers, each condenser comprising a plurality of stator plates and a plurality of rotor plates cooperating therewith, and means for equalizing the capacities of said condensers when in their maximum capacity positions, comprising a rotor plate for each condenser, shaped similarly to the other rotor plates and rotatable therewith and axially movable with respect thereto.

2. In a radio receiver, in combination, a plurality of condensers adapted to adjust associated tuned circuits to corresponding wave lengths at corresponding settings of the condensers, each condenser having a plurality of stator plates and a plurality of rotor plates cooperating therewith, means for operating said rotor plates of all or" the condensers in unison, and means for equalizing the capacities of: said condensers when in their maximum capacity positions, comprising a rotor plate for each condenser shaped similarly to the other rotor plates and rotatable therewith and axially movable with respect thereto.

In testimony whereof, I have signed my name to this specification this 17th day of August, 1925.

ALBERT S. BLATTERMAN. 

